Estrogen-regulated gene expression in human osteosarcoma cells stably transfected with estrogen receptor alpha or beta. Homo sapiens

Estrogens exert many important effects in bone, a tissue that contains both estrogen receptors alpha and beta (ERalpha and ERbeta). To compare the actions of these receptors, we generated U2OS human osteosarcoma cells stably expressing ERalpha or ERbeta, at levels comparable to those in osteoblasts, and we characterized their response to estradiol (E2) over time using Affymetrix GeneChip microarrays to determine the expression of approximately 12,000 genes, followed by quantitative PCR verification of the regulation of selected genes. Of the ca. 100 regulated genes we identified, some were stimulated by E2 equally through ERalpha and ERbeta, whereas others were selectively stimulated via ERalpha or ERbeta. The E2-regulated genes showed three distinct temporal patterns of expression over the 48 h time course studied. Of the functional categories of the E2-regulated genes, most numerous were those encoding cytokines and factors associated with immune response, signal transduction, and cell migration and cytoskeleton regulation, indicating that E2 can exert effects on multiple pathways in these osteoblast-like cell lines. Of note, E2 up-regulated several genes associated with cell motility selectively via ERbeta, in keeping with the selective E2 enhancement of the motility of ERbeta-containing cells. On genes regulated equally by E2 via ERalpha or ERbeta, the phytoestrogen genistein preferentially stimulated gene expression via ERbeta. These studies indicate both common as well as distinct target genes for these two ERs, and identify many novel genes not previously known to be under estrogen regulation. Keywords: other

雌激素可在骨组织中发挥诸多关键生理效应，骨组织同时表达雌激素受体α和β（estrogen receptors alpha and beta，ERα和ERβ）。为对比这两种受体的生物学功能，我们构建了稳定表达ERα或ERβ的人类U2OS骨肉瘤细胞系，其受体表达水平与成骨细胞中的内源水平相当。随后我们采用Affymetrix GeneChip微阵列技术，对该细胞系在雌二醇（E2）处理下的时序基因表达谱进行检测，覆盖约12000个基因的表达分析，并通过定量PCR对筛选得到的部分差异调控基因进行验证。
我们共鉴定到约100个受E2调控的基因，其中部分可被E2通过ERα和ERβ同等激活，而另一些则仅能被ERα或ERβ选择性激活。在本次研究的48小时时序周期内，受E2调控的基因呈现三种截然不同的时间表达模式。对这些调控基因的功能分类分析显示，编码细胞因子、免疫应答相关因子、信号转导分子以及参与细胞迁移与细胞骨架调控的基因数量最为丰富，这表明E2可通过多条通路影响此类成骨样细胞系的生物学过程。
值得注意的是，E2可通过ERβ选择性上调多个与细胞运动相关的基因，这与ERβ阳性细胞的运动能力可被E2选择性增强的现象相符。对于可被E2通过ERα和ERβ同等调控的基因，植物雌激素染料木黄酮（genistein）更倾向于通过ERβ激活其基因表达。本研究既鉴定了这两种ER共有的靶基因，也发现了二者各自独特的靶基因，同时还发现了诸多此前未被报道受雌激素调控的新基因。关键词：其他